Editor's Note:This is the last in a 10-part
LiveScience series on the origin, evolution and future of the human
species and the mysteries that remain to be solved.

The past of human evolution is more and more coming to light as
scientists uncover a trove of fossils and genetic knowledge. But where
might the future of human evolution go?

There are plenty of signs that humans are still evolving. However, whether humans develop along the lines portrayed by hackneyed science fiction is doubtful.

Clichés dashed

An old cliché has the highly evolved humans of the future sporting
large heads to hold their advanced enlarged brains, "but that's
nonsense, whole nonsense," said paleontologist Peter Ward at the
University of Washington at Seattle, author of "Future Evolution."

"If you've ever gone through a childbirth or witnessed one," Ward
says, "we're already anatomically right on the edge of how big our
heads can go — our big brains have already caused extreme problems in
childbirth, and if we had bigger and bigger brains, that'd cause more
mothers to die in childbirth, so evolution would select against that."

Another idea, suggested by evolutionary theorist Oliver Curry of the London School of Economics, seems like a retread of ideas
from science fiction writer H.G. Well's classic "The Time Machine,"
with the human species split in two over time — an underclass of
dim-witted, short goblins, and a genetic upper class of tall, slim,
healthy, attractive, intelligent and creative superhumans that
eventually are spoiled by technology that will do everything for them,
resembling domesticated animals.

"That's crap," Ward said. "Why would that happen? Are we like blind
cavefish? After we get Google, do we get stupider? Intelligence is
coded on too many genes to just lose a trait like intelligence. That's
not going to happen."

As to whether humans will evolve to lose the arguably extraneous
pinky for a cartoonish four-fingered hand, "that's crap," Ward said.
"We've had five fingers for a long time. What aspect of natural
selection would opt for four? Once a body plan seizes upon a number of
digits, it doesn't change unless there's a damn good reason. It made
sense for the horse to go down to a single hoof, but I can't think of
why we would lose fingers."

Ward suggests that, if left untouched, humans might converge in
appearance as populations mix. "I kind of view us all as eventually
having chocolate-covered hair and medium stature, getting rid of all
extremes," he speculated. "Of course, the big elephant in the room, the
change from the past that you cannot ignore when talking about the
future of human evolution, is genetic engineering."

Genetic engineering

Humanity now has an unparalleled means by which to direct our
evolution — genetic engineering. By using viruses and other techniques,
we can in theory modify our genomes, and over time, scientists may
uncover genes underlying intelligence, health, athletic prowess, longevity
and other desirable traits, engineering what might seem like superhuman
progeny. Genetic engineering is how Ward speculated new species of
humans might emerge.

"Let's say we create someone that can live 100 or 120 years," he
said. "If you know you can live up to then, your whole pattern of
investing could radically change. The amount of money that you could
invest would go way, way, way up, and then economic incentives could
drive selection away from mating with other creatures to seek out those
similar to you."

Once populations are separated, given enough time and near-total
lack of interbreeding, you would get divergence, he conjectured.
Although short-lived humans could genetically engineer their own
offspring for longevity, Ward suggested that interbreeding between
populations would still remain low.

"I think taboos would arise which would prevent mating between
populations — 'I don't want them anymore' or 'We want natural people,'"
he said. "Of course this is all pure speculation, but this is the only
way I can see new human species emerging — unless we get off the
planet."

The final frontier

Another way new human species might occur is if we finally leave the cradle of our home world.

"If you want to make a new species, you have to really separate
populations out," Ward said. "If we're all holed up on Earth, I don't
see new species emerging, unless of course we engineer one. However, if
we get some populations to split off by sending them off to space
colonies, where they might evolve under different environments, it's
possible."

The challenges entailed with leaving the solar system "could mean we
might not ever colonize another star," Ward said. "But it could be that
genetic engineering could make it possible."

Besides reducing human size to make travel easier on spaceship life
support systems, Ward noted his colleague Mark Roth of the Fred
Hutchinson Cancer Research Center in Seattle is conducting research to put humans into a hibernation-like state by having people inhale hydrogen sulfide.

"We might actually start selecting for the types of brain or nervous systems that allow one to go into hibernation," Ward said.

Our technology might readily spin us far past human shapes. Science
fiction has long speculated as to whether or not we might one day be
able to download our brains into computers or engineer bodies that can
perform like spaceships.

"We're opening up new ways of evolving involved with machines," Ward said.

Charles Q. Choi

Charles Q. Choi is a contributing writer for Live Science and Space.com. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica.